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Red idiot light on bright - ideas?

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RickB

RickB

Yoda
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Coming home on the freeway this afternoon the red light came on bright. So far I have opened up the hood & checked to see if my fan belt was on and if the wires were plugged in to the back of the alternator.
Going out now to meter things & see if I've got charging or not.
Any ideas guys?
I'll take the laptop out and check for your thoughts - I need this car to be running tomorrow morning.

For those who don't already know - this is the 78 Midget with the Nissan 1500 motor. It has an alternator.

Thanks!
 
Just guessing at this point with nothing else to go on, but if all wires are intact, I would suspect a faulty voltage regulator!
 
bugimike said:
Just guessing at this point with nothing else to go on, but if all wires are intact, I would suspect a faulty voltage regulator!
Click to expand...

Thanks, but I don't see one.
I wonder if that inside the altrnator?

I get 13.02 VDC from Battery with car turned off and 14.04 vdc when car is running.
 
Yes. Alternators have solid state regulators as well as AC/DC converters built into them.
 
Running with lights on bright 12.6 vdc
Revving engine produces 14.8 vdc

This seems kind of normal - do I have a warning light gone crazy?
 
It could be in the ignition switch or I suppose that light must be activated by a relay of sorts. Because it is usually on breifly when starting. That light signifies that power has gone into the alternator to activate the charging system. It should charge even when fully lit. If it was not lit it may not. I would consult a wiring diagram and see if that light has a relay powering it. If not and the vehicle is charging (which your specs do sound fine), I would suspect a problem with the ignition switch.
 
Maybe you should put oil in it!

Seriously though. The charging light gets +12V power from the ignition switch when the switch is turned on. A ground is made in the regulator (which is inside the alternator). When the alternator starts charging, the regulator supplies the light with +12V power, making the warning light turn off. (power on both poles)
If the light is on, it could be shorting on either side, defective ignition switch, defective regulator.
It appears that it is charging properly with the voltage readings you supplied.
 
My thought was also in the internal wiring to the warning light!!
 
<div class="ubbcode-block"><div class="ubbcode-header">Quote:]Maybe you should put oil in it![/QUOTE]

Donn maybe on to something. I switched the leads on my car so that the red light is my oil light. I did this because I did not feel like the amber light was "urgent" enough. I wanted to make sure that if that light came on while my wife was driving the car, she would see it and STOP!

Perhaps your DPO did the same thing. Probably worth checking.
 
Thanks guys,

Scott, I will take a look at the ignition.

Morris - the light operated normally up until yesterday.
It comes on brighter with higher revs, a little dimmer at idle.

Mike - I'll never discount the possibility that the wiring could be at fault :wink:
Might just be something under the dash - about a week ago I pulled the wires off the dash light dimmer & jumpered them so I could get some decent dash lights - maybe there's something in there that I messed up. Strangely though it was all fine until yesterday.

I need to follow the wiring and make sure there's no chafing. If there is an unintended ground on that circuit it seems to be pretty darn solid, with the motion of the car it would flicker if it was just a wire touching ground loosly.

I drove it this morning, lights on bright, electric fan running, heater fan on. Everything seems to run normally except the light. I am not saying everything is good, just that everything except the light 'seems' good.
 
And of course the bulb is good?
 
:iagree: Which is where I started in the first place!! Regulators can be fickle things when they go bad!!! If you had mentioned the variations in brightness and flickering up front.... :thumbsup:
 
Please allow me to rephrase...

There is no flickering.

It seems to dim just a bit at idle and get stronger when I step on the gas, this is easier to see in the dark (when I leave home in the morning).

The dash lights and the headlights dim just a bit at idle and get stronger when I step on the gas in tandem with the red light.

Yes Jack, the light bulb seems to work. :wink:
It goes off when I turn the key off and comes on (stays on) when I start the car.
 
I see, when I said this:

<div class="ubbcode-block"><div class="ubbcode-header">Quote:]If there is an unintended ground on that circuit it seems to be pretty darn solid, with the motion of the car it would flicker if it was just a wire touching ground loosly.[/QUOTE]

I meant that <span style="font-weight: bold">if there was a wire grounding loosely</span> I would expect to see some flickering - there is no flickering so it must be something else.

If my regulator is inside the alternator then does that mean I have to get a new alternator?
 
New... or re-built.

Remove the alternator and take it to your local chain auto parts store (Advance, AutoZone, etc.) They will bench test the alternator for free and will probably be able to offer you a rebuilt unit with a lifetime warranty for a reasonable price. You did say this was a Nissan transplant didn't you? It's much more likely that they'll have a rebuilt Nipondenso alternator than the traditional Lucas unit.
 
Thanks Doug, yes that sounds like the thing to do.
Easy enough too, if it isn't raining this afternoon. :wink:
 
The bulb burned out on the way home today - I take that as a bad sign.
It is simply too wet out to do any work on it today, we will see what the weekend holds for Spridgiting around.
 
Somehow, I'm not surprised, given the voltage fluctuations it sounded like it was going through! Then again, it will be interesting to see what happens when you replace the bulb (could it have been "going bad" - it's a long shot, and I still think it might be a regulator problem!) :rolleyes:
 
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